Damaged Watersheds in West Kalimantan - 969,000 ha in Critical Condition: Massive Flooding Ensued

The massive floods in West Kalimantan may have been caused by the La Nina phenomenon, however the damaged watersheds have worsened the situation.

An area of 969,000 hectares which functions as the watersheds (drainage basins) in West Kalimantan, Indonesia, is in critical condition and damaged. This is considered to be one of the factors that caused the widespread flooding in the province which started in October, 2021. 

The damaged watersheds multiplied by the high rainfall due to La Nina phenomenon have caused widespread flooding in West Kalimantan province which is located on Borneo Island. 

“Globally, there are about 969,000 hectares of watersheds in West Kalimantan experiencing land damage and in critical (condition). The largest is the Kapuas Watershed," said Head of the Kapuas River Basin and Protected Forest Management Center, Ministry of Environment and Forestry, Remran as quoted from Kompas, Monday (15/11/2021). 

Flood conditions at the Simpang Lima Monument in Sintang Regency, West Kalimantan, Tuesday (9/11/2021). The damaged watersheds may have contributed to the incident. (BNPB/Danung Arifin Disaster Communications)
Flood conditions at the Simpang Lima Monument in Sintang Regency, West Kalimantan, Tuesday (9/11/2021). The damaged watersheds may have contributed to the incident. (BNPB/Danung Arifin Disaster Communications)

 According to the USGS, a watershed is an area of land that drains all the streams and rainfall to a common outlet such as the outflow of a reservoir, mouth of a bay, or any point along a stream channel. The word "watershed" is used interchangeably with drainage basin or catchment. Damaged watershed may cause massive flooding just like what is currently happening in Kalimantan.

For information, there are four prioritized drainage basins in West Kalimantan. 

  • Kapuas watershed covers an area of ​​9,659,789 million hectares.
  • Pawan watershed, covers 1,144,425 million hectares area.
  • Sambas watershed, covers 746,414 hectares area.
  • Mempawah watershed, covers 181,382 hectares area.

Read also: Thousands of Houses are Flooded and 15 People are Swept Away as La Niña Bears Down on Indonesia

The most extensive area is the Kapuas watershed. This area crosses seven regencies and cities, namely Pontianak City, Landak Regency, Sanggau Regency, Sekadau Regency, Melawi Regency, Sintang Regency, and Kapuas Hulu Regency.

Additionally, Remran stated that Lake Sentarum in Kapuas Hulu has experienced degradation due to land conversion. He stated that  there is still a lot of exploitation of natural resources in the mining and plantation sectors.

"From the topography point of view, there is a basin in the upper watershed, now it has been degraded due to land clearing," said Remran.

As of Saturday, 13 November 2021, Sintang Regency is still suffering from massive flooding. According to Indonesian National Board for Disaster Management (BNPB), a total of 10,381 families or 33,221 people are still displaced. The flood has affected 87,496 people in total. Previously, it was reported that the maximum water level is about 300 centimeters or approximately 10 feet.

The victims come from 9 sub-districts that have been affected by the floods since October 21, 2021. Lack of clean water, widespread diarrhea, and skin disease have been reported in refugee camps. 

BNPB also reported that floods are still ongoing in Sekadau Regency as of Friday, November 12, 2021. Local authorities stated that the water depth is in range between 50 and 310 cm. As many as 931 families or 3,385 people are still living in the refugee camps

As for the population, the latest data recorded that as many as 5,449 families or 19,560 people spread across four sub-districts in Sekadau Regency have been directly affected by the flood which started since October 26, 2021.

Meanwhile in a neighboring province, Central Kalimantan, floods also hit eight sub-districts in East Kotawaringin Regency, since last November 10, 2021. As of, Sunday 14 November, 2021, the flood still has not subsided. The local disaster management agency reported that there were no fatalities as a result of the incident. This flood inundated 576 housing units and 2 educational facilities with water levels ranging from 10 - 100 centimeters.